1. Field of the Invention
The invention relates to liquid detergent formulations containing hydroxypropyl methylcellulose ethers. The compositions exhibit improved stability characteristics, especially during low temperature storage.
2. The Prior Art
Cellulose ethers have long been recognized as thickening, soil-shield and anti-redeposition agents in liquid detergents. Soil-shield is the protective coating of cellulosic deposited onto synthetic fabric during a wash in a detergent containing both a surfactant and a cellulose ether. Removal of oil and grease stains is facilitated in subsequent washes where fabrics have been soil-shield treated. Anti-redeposition agents function to prevent soil from re-settling on fabrics after it has been removed during washing.
Whether used for thickening or laundering purposes, the cellulose polymers frequently become incompatible with the liquid detergent compositions. Solid builders, inorganic salts and various hydrophobic components all contribute to the destabilization of the cellulose polymer in these formulations.
Freeze-thaw and low temperature storage stability is particularly poor with cellulose ethers in built, mixed anionic-nonionic liquid detergents. In cold weather, agglomeration of the cellulose ether occurs with resultant separation from the liquid. Concomitantly, the liquid's viscosity is altered.
It is an object of the present invention to overcome the freeze-thaw and low temperature storage instability of heavy duty liquid detergents containing cellulose ether.
A further object of this invention is to provide a stable heavy duty liquid detergent containing cellulose ether exhibiting soil-shield and anti-redeposition benefits.